Doom 3: Phobos is a 1 episode project which continues the story in Doom 3. It is set in between Doom 3 and its expansion pack, Resurrection of Evil. Doom 3: Phobos will feature more variation than the original 2004 game, and will bring back more of the traits that made the original Dooms successful.
Doom 3: Phobos has evolved into a very extensive and ambitious project. We are well on our way of creating an unofficial expansion pack of top quality.